A production process of producing a film, especially a functional film, includes various drying steps such as drying after washing and drying after coating.
In a case where a separator film to be used as a functional film in a lithium ion secondary battery is taken as an example, Patent Literature 1 discloses a technique for providing one side of a film with a layer for achieving higher heat resistance.
Specifically, Patent Literature 1 discloses (i) coating a film with a heat-resistant coating solution with use of a coating device and then (ii) causing the coated film to pass through a dryer so as to dry the coated film.